(a) Field of the Invention
The present invention relates to a vehicle speed detecting system, and a vehicle speed detecting method using the same, and more particularly, to a vehicle speed detecting system capable of accurately detecting a speed of a vehicle at a low speed and a high speed, and a vehicle speed detecting method using the same.
(b) Description of the Related Art
In a method of sensing a speed of a vehicle, a pulse ring is installed at an output side of a transmission, and a sensor is adjacently installed to the pulse ring, where the sensor senses a rotation speed by sensing a change in amplitude of a voltage generated by a hall effect.
A wheel speed sensor installed in each wheel for an ABS or a VDC senses a speed by the same principle. In particular, a change in a magnetic field due to a rotation of the pulse ring generates a voltage in a sensor coil, and the fine voltage drives a transistor again to transmit rotation information on the sensor to a processor. A size of the voltage generated at this time is determined by a distance between the sensor and a conductor.
FIGS. 8 and 9 (RELATED ART) are drawings illustrating a conventional vehicle speed detecting system and output waveforms thereof.
FIG. 8 (RELATED ART) illustrates a configuration in which a pulse ring rotation part 102 of a pulse ring 100 is provided with four conductors (pitch units) 104 (FIG. 8(a)), and output waveform graphs of the pulse ring at a low speed (FIG. 8(b)) and a high speed (FIG. 8(c)) according to the configuration, and a sensor 120 is adjacently provided to the pulse ring 100.
FIG. 9 (RELATED ART) illustrates a configuration in which a pulse ring rotation part 202 of a pulse ring 200 is provided with 12 conductors (pitch units) 204 (FIG. 9(a)), and output waveform graphs of the pulse ring at a low speed (FIG. 9(b)) and a high speed (FIG. 9(c)) according to the configuration, and a sensor 220 is adjacently provided to the pulse ring 200.
In a case where the four conductors (pitch units) 104 are provided, the appropriate number of output waveforms for detecting a vehicle speed is detected at the high speed as illustrated in FIG. 8(c), so that it is possible to accurately calculate the speed, but the number of output waveforms detected at the low speed is small as illustrated in FIG. 8(b), so that it is difficult to accurately calculate the speed.
In a case where the 12 conductors (pitch units) 204 are provided, the appropriate number of output waveforms for detecting a vehicle speed is detected at the low speed as illustrated in FIG. 9(b), so that it is possible to accurately calculate the speed, but the number of output waveforms detected at the high speed is excessive as illustrated in FIG. 9(c), so that a processor having excellent calculation performance is required in order to accurately calculate the speed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.